如何使UIBarButton在IPhone中正确对齐

我已经动态添加了

工具栏

，并且动态添加了

按钮

，但它显示在左侧，我希望它显示在右侧。 有人能帮我吗我的代码是这样的

 CGRect frame = CGRectMake(0, 205, 320, 40);
 UIToolbar *toolbar = [[UIToolbar alloc]initWithFrame:frame];
 toolbar.barStyle =UIBarStyleBlackTranslucent;
 toolbar.tintColor = [UIColor darkGrayColor];


 UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle: @"Done" style:UIBarButtonItemStyleDone target:self action:@selector(foo)];
 NSArray *array = [[NSArray alloc]initWithObjects:backButton,nil];

 [toolbar setItems:array];

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我通过简单地添加以下行得到了答案

UIBarButtonItem*BtnSpace=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarbuttonSystemFlexibleSpace目标：自我操作：无]

并将其添加到数组中 现在代码如下所示

 CGRect frame = CGRectMake(0, 205, 320, 40);
 UIToolbar *toolbar = [[UIToolbar alloc]initWithFrame:frame];
 toolbar.barStyle =UIBarStyleBlackTranslucent;
 toolbar.tintColor = [UIColor darkGrayColor];


 UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle: @"Done" style:UIBarButtonItemStyleDone target:self action:@selector(foo)];
 NSArray *array = [[NSArray alloc]initWithObjects:backButton,nil];

 [toolbar setItems:array];

self.tableView=[[UITableView alloc]initWithFrame:CGRectMake（0,20,320,480）style:UITableViewStyleGrouped]； CGRect帧=CGRectMake（0,205,320,40）； UIToolbar*工具栏=[[UIToolbar alloc]initWithFrame:frame]； toolbar.barStyle=uibarstyleblacktransparent； toolbar.tintColor=[UIColor darkGrayColor]

UIBarButtonItem *BtnSpace = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle: @"Done" style:UIBarButtonItemStyleDone target:self action:@selector(foo)];
NSArray *array = [[NSArray alloc]initWithObjects:BtnSpace,backButton,nil];

[toolbar setItems:array];